GB2504530A

GB2504530A - Solar panel cleaning element

Info

Publication number: GB2504530A
Application number: GB1213727.9A
Authority: GB
Inventors: Paolo Trabacchin
Original assignee: Nidec Control Techniques Ltd
Current assignee: Nidec Control Techniques Ltd
Priority date: 2012-08-02
Filing date: 2012-08-02
Publication date: 2014-02-05
Anticipated expiration: 2032-08-02
Also published as: GB2504530B; GB201213727D0

Abstract

A solar panel 2 and a cleaning element are disclosed. The cleaning element is secured with respect to the solar panel and has a free portion 18 arranged to be disturbable by an airflow to flay an outer surface of the solar panel 2, thereby displacing material on the surface. The cleaning element may comprise a transparent flexible strip 2 and the airflow is preferably normal wind conditions.

Description

Solar panel cleaner The present disclosure relates to the cleaning of solar panels.

Photovoltaic solar panels rely on sunlight to produce electricity. A solar panel comprises cells that rcccivc sunlight and convert it to electricity through thc photovoltaic effect. In most solar panels, the cells are covered by a transparent covering, which protects the cclls from moisture and general weather damage, while enabling sunlight to reach the cells through the transparent covering.

Solar panels are often strategically located in sites that receive a large amount of sunlight and at an angle to optimise the amount of light incident upon the cells. A particular example of such a site is a hot desert environment. Such locations may be remote from human inhabitations.

Over time, the transparent covering will accumulate dirt, sand, earth or other unwanted material on its outer surface. This is particularly an issue in windy environments, in which such materials are carried with the wind and deposited onto the solar panels. The angle of a typical panel does not encourage the material to remove itself due to the wind or being washed off by rain if and when any falls. Indeed the rain itself may contain particulate matter that will add to the accumulation of material.

The accumulation of unwanted material on the surface of the transparent covering causes a reduction in the amount of light that reaches the cells. This causes a corresponding reduction in efficiency of the cells in producing electricity. Due to the commonly employed series' arrangement (string) of electrical connections of individual solar cells within a solar panel, if one cell is shaded the power output of the entire string is severely affected.

The recognised way to address this problem is to clean the panels to remove the material from the surface of the transparent covering. At present, this is achieved either manually or using a powered cleaning device.

The present inventor has recognised that manual cleaning of solar panels is time-consuming and labour-intensive, particularly if the solar panels are in a remote location. The power output will begin to reduce soon after cleaning, as unwanted material will soon begin to build up again on the surface. The cleaning must therefore be carried out at regular intervals, and operation between these intervals will be at a generally reduced power output level.

The present inventor has also recognised that the use of a powercd cleaning device to clean the surface of a solar panel has the disadvantage that it requires electricity. Such powered cleaning devices also tend to be complex mechanical devices that are themselves susceptible to damage caused by weather conditions. These complex devices will also require maintenance and repair due to their complexity. Their complexity means that they arc difficult to manufacture, and the manufacturing process involves high costs as a result of this. Their complexity also makes these devices difficult to install on a solar panel. As with manual cleaning, the power output of the solar panel will begin to reduce soon after the powered cleaning device has operated, and the cleaning device must therefore be operated at regular intervals, with operation between these intervals being at a generally reduced power output level.

An invcntion is set out in claim 1. Optional features are set out in the dependent claims.

According to an aspect, there is provided in combination a solar panel and a cleaning element, the cleaning element being secured with respect to the solar panel and having a free portion arranged to be disturbablc by an airflow to flay an outer surface of the solar panel, thereby displacing material on the surface.

According to an aspect, there is provided a solar panel cleaner comprising: a cleaning element comprising a first portion and a free portion; and a securing arrangement arranged to secure the first portion of the cleaning element with respect to a solar panel such that the free portion of the cleaning element is disturbable by an airflow to flay an outer surface of the solar panel, thereby displacing material on thc "ace.

A solar panel cleaner according to the present disclosure overcomes the disadvantages discussed above with respect to both the manual and powered cleaning options. Cleaning of the solar panel with the present cleaner occurs substantially continuously, which means that the surface is maintained in a relatively clean state, rather than gradually accumulating significant amounts of unwanted material between cleaning opcrations. This cnsurcs that the power output of the cells is consistently at or near its maximum level.

The disclosed cleaner does not require manual operation, hence the time and labour cost implications of manual cleaners described above do not apply.

The disclosed cleaner does not require electricity. This means that it does not reduce the net useful power output from the solar panel site, as described above for powered cleaning devices. While the powered cleaning devices described above are becoming more and more complex in an effort to improve solar panel cleaning, the present cleaner goes against this trend in the art by being substantially less complex than these devices. This means that maintenance and repair requirements and operating costs are substantially reduced or even eliminated. The difficulty of manufacture and cost of producing the present cleaner are also significantly lower than for powered cleaning devices as described above. Similarly, the present cleaner can be installed on a solar panel easily, unlike the powered cleaning devices as described above.

In some embodiments, the cleaning element is transparent, thereby enabling light to pass through it and reach the cell, even while cleaning is in operation. This is a further improvement over the manual or powered cleaning options described above, as in these options the panels are obscured while cleaning takes place, thus reducing the power output of the solar panels during cleaning. The present cleaner is therefore able to operate without substantially reducing the power output during the cleaning operation.

Embodiments are now described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional view of a solar panel and a solar panel cleaner; Figure 2 is a schematic plan view of an array of solar panels and four solar pane! cleaners.

With reference to Figure 1, a photovoltaie solar panel 2 comprises a ccl! 4 and a covering 6. The cell 4 is configured to convert received!ight into e!ectrical energy using the photovoltaic effect. The covering 6 is arranged to cover the light-receiving part of the cell 4.

The covering 6 is substantially transparent such that light from a light source 8 (e.g. the sun) external to the solar panel 2 is able to illuminate the cell 4 through the covering 6. The covering 6 comprises a light-receiving surface 10 that is exposed and located on the outside of the solar panel 2. A base surface 12 of the solar panel 2 is exposed on the opposite surface of the solar panel 2 to the!ight-reeeiving surface 10 and is substantia!ly para!le! to the light-receiving surface 10. A first side 14 of the so!ar pane! 2 is exposed and extends between the light-receiving surface 10 and the base surface 12, and is substantial!y perpendieu!ar to each of these surfaces. The solar panel 2 is of typical dimensions.

A solar panel cleaner 15 comprises a clamp 16 and a strip 18. The clamp 16 is secured to the solar panel 2 adjacent the first side 14 of the solar panel 2. The clamp 16 grips a respective part of each of the light-receiving surface 10 and the base surface 12, at a location proximal to the first side 14. The clamp 16 is therefore in a fixed position relative to the solar panel 2 and acts as a securing arrangement. The clamp 16 is adjustable to be securable to solar panels 2 of different dimensions.

The strip 18 has a free end 20 and a secured end 22. The secured end 22 is secured to the clamp 16. The free end 20 of the strip 18 is moveable while the secured end 22 of the strip 18 remains secured to the e!amp 16. The strip 18 is arranged to extend across the light-receiving surface 10. The strip 18 has a sufficient longitudinal extent between the secured end 22 and the free end 20 to enable the free end 20 to reach an opposed side 24 of the solar panel 2 opposite the first side 14 that is adjacent the clamp 16, while the secured end 22 remains secured to the clamp 16. The range of movement of the strip 18 is therefore such that the strip 18 can be brought into contact with any part of the light-receiving surface 10 of the solar panel 2.

The strip 18 has a width that is substantially shorter than its length. The width is of suitable dimension to enable to the strip 18 to be disturbed by normal wind conditions, while not so wide as to cover more than a small part of the light-receiving surface 10 at any one moment. The thickness of the strip 18 is substantially shorter than its width, such that the strip 18 is able to deform easily, is flexible and is lightweight, thus facilitating disturbance by the wind. The dimensions of the strip 18 arc determined such that they arc appropriate for cleaning the solar panel 2 with which the strip 18 will be used, and are appropriate for the weather conditions at the location where the solar panel 2 is to be situated. In this embodiment, the strip 18 has a length of about 50 cm, a uniform width of about 3 cm and a uniform thickness of about 0.1 mm.

The strip 18 is made of suitable material for it to be disturbed by normal wind conditions while having sufficient resilience so as not to wear out quickly or break as it is disturbed. It is flexible and able to be bent and twisted by normal wind conditions, while maintaining its integrity. In this embodiment, the strip 18 is made of polythene.

The strip 18 is transparent, thereby enabling light to pass through it and reach the cell 4 via the transparent covering 6.

In use, the strip 18 is disturbed by the wind and moves in an unpredictable manner as it is blown by the wind to flay the light-receiving surface 10 of the solar panel 2. The movement of the strip 18 inevitably includes movements across parts of the light-receiving surface 10. As the strip 18 moves across parts of the light-receiving surface 10, it dislodges any unwanted material that has become stuck to these parts of the light-receiving surface 10.

The dislodged material is then free to be blown away by the wind or is flicked off by the movement of the strip 18. Over time, the strip 18 will pass over the entire surface. The removal of the dislodged material from the light-receiving surface 10 allows more light to reach the cell 4, and hence increases the power output of the solar panel 2.

With reference to Figure 2, an array of solar panels 2 is shown with four solar panel cleaners 15. The strip 18 of each solar panel cleaner 15 has a sweeping radius that covers at least part of a plurality of light-receiving surfaces 10 of respective solar panels 2. The Teprng radius is determined by the length of the strip 18, with a longer strip 18 having a larger sweeping radius. As the sweeping radius increases, the number of solar panel cleaners required to clean an array of solar panels 2 decreases, as each solar panel cleaner 15 is able to clean a plurality of the solar panels 2 in the array. In the example arrangement of Figure 2, four solar panel cleaners 15 are used to clean a substantial majority of the total surface area of the light-receiving surfaces 10 of thirteen solar panels 2.

It will be understood that the above description of specific embodiments is by way of cxamplc only and it is not intcndcd to limit thc scope of the prcscnt disclosure. Many modifications of the described embodiments, some of which arc now described, arc envisaged and intended to be within the scope of the present disclosure.

In some embodiments, alternative arrangements of solar panel cleaners in an array of solar panels are implemented instead of that of Figure 2. For example, there may be one solar panel cleaner per solar panel, or per pair of solar panels, or per four solar panels in a 2x2 arrangement with the secured end of the cleaner in the centre of this arrangement. In some embodiments, the sweeping arrangements of different solar panel cleaners partially overlap each other to ensure frill coverage of each light-receiving surface in the array. The dimensions of the solar panel cleaners are configured accordingly.

While the strip described above is transparent, in some embodiments the cleaning element is translucent or opaque.

In some embodiments the cleaning element (which acts as a flaying means) is made of any suitable material that is flexible and sufficiently durable. The material of the cleaning element in the embodiment described above is polythene. Other plastics materials and rubbers can be used. Synthetic and non-synthetic fabrics or cloths can be used to equal effect. The cleaning element will be subject to wear. The choice of material, particularly its durability, will require consideration of cost and frequency of replacement often in remote locations.

While the strip described above has the dimensions set out above, in some embodiments the cleaning element has different dimensions. In some embodiments, the cleaning element is not a strip but forms another shape, such as a rod. The strip or other tning element may have plain edges or have another profile such as a corrugation.

Intermittent contact of the clement along its length may encourage its movement in lighter wind thereby improving the cleaning action.

While the strip and clamp described above are separate components, in some embodiments the cleaning element and the securing arrangement are integrally formed.

In some embodiments, different securing arrangements are used instead of the clamp described above, such as the cleaning element being secured with respect to the solar panel by adhesive tape or glue.

In some embodiments, the cleaning element is secured to a structure proximal to the solar panel but not itself attached to the solar panel. The secured end of the cleaning element is still thereby secured relative to the solar panel.

In some embodiments, the solar panel is not a photovoltaic solar panel but is another type of solar panel such as a solar hot water panel.

The cleaning element may be powered by being caught in the wind itself However, in alternative embodiments the cleaning element is attached to another device, such as propeller, that catches the wind and imparts a cleaning motion to the element that flays the surface of the panel.

Claims

C LA I MS1. In combination a solar panel and a cleaning element, the cleaning element being secured with respect to the solar panel and haying a free portion arranged to be disturbable by an airflow to flay an outer surface of the solar panel, thereby displacing material on the surface.
2. The combination of claim 1, wherein the cleaning clement comprises a flexible strip.
3. The combination of any preceding claim, wherein the cleaning element is transparent or translucent.
4. The combination of any preceding claim, wherein the cleaning element is secured with respect to the solar panel by a securing arrangement.
5. The combination of claim 4, wherein the securing arrangement comprises a clamp.
6. The combination of claim 4 or claim 5, wherein the cleaning element and the securing arrangement are integrally formed.
7. The combination of any preceding claim, wherein the airflow corresponds to normal wind conditions.
8. The combination of any preceding claim, wherein the outer surface of the solar panel comprises a surface of a transparent covering of the solar panel.
9. The combination of any preceding claim, wherein the solar panel is a photovoltaic solar panel.